Hi all,
have a problem I hope someone can direct me to the answer.
1985 Blazer M1009
shifts from first to second at 40 mph and then shifts to third at 60 mph.
then down shifts from third to second at 40 mph
Can anyone on the list tell me were I can adjust this shifting speed? I know
it must be either vacuum or switch?
anyone??
this unit has stock 6.2 D with TH400 transmission.

thanks in advance for any help here.

whoha.

this is my first post so I hope this is in the right area???

Your 6.2 diesel w/TH 400 trans has a vacum regulator at the front of the engine. First check the big vacum hose coming from vacum pump ( rear of engine ) and make sure it is putting out a constant 25 in and the hose is not leaking. You must then put a vacum gage inline on the hose going to the trans modulator. Vacum can be adjusted by moving regulator ( loosen 2 screws ) and watch vacum gage. You will want about 13 to 15 in. at idle and gage must drop to 5 in or lower when throttle is snapped open. This must all be done with engine running and your hands being very close to fan. THIS IS DANGEROUS and should be done by a professional. You can lose a hand if it gets caught up in the fan. Watch it!
mike

thanks for the help.

whoha